The quality of the image transfer from an intermediate transfer member (“ITM”) to a substrate is sensitive to the pressure between the ITM and the substrate which is governed, inter alia, by the spacing (usually negative spacing) between the undeformed ITM and an impression roller. If contact pressure between the substrate and ITM is too high, the blanket can lose its release capability.
On the other hand, if contact pressure between the ITM and substrate is too low, fixing of the ink to the substrate is marginalized, and blanket contamination can cause early blanket failure. If pressure is not substantially the same for all regions along the nip, a section of the print and blanket can fail for the same reasons as the low and high pressure failures.
In existing printers the (negative) spacing and (indirectly) the pressure between the ITM and the substrate on the impression roller is performed manually. It is known that different pressures are required for different print media depending, depending inter alia on the type of media (material, surface finish, smoothness, coating) to which the image is transferred in second transfer. However, due to the variations in other parameters, such as ITM blanket thickness, in the end, the process of second transfer calibration is essentially a manual one.